Creating a robust and reusable cell immobilization system for bioethanol production by thermotolerant yeast using 3D printing and soybean waste

Cell immobilization is a technique that reduces the lag phase of cell growth and improves microbial stress tolerance, resulting in an increased product yield. In this study, a new immobilization carrier was prototyped using 3D printing for thermotolerant Kluyveromyces marxianus to produce bioethanol. Upon coating with soybean meal (SM) waste, new functional groups were introduced and the surface roughness was enhanced significantly (p < 0.05). Fermentation of the immobilized SM-coated templates showed a marked improvement (p < 0.05) of bioethanol production and productivity, from 37 g/L and 1.71 g·L−1·h−1 in a suspension culture to up to 45 g/L and 2.82 g·L−1·h−1, translating to an 11 % and 60 % increase in theoretical yield and productivity, respectively. Even after 30 cycles of repeated batch, the yield and productivity remained relatively stable. These findings highlight the physical durability, stability, and commercial potential of 3D-printed templates coated with SM as cell immobilization carrier.